Ground fault monitoring system

ABSTRACT

A ground fault monitoring system includes a ground fault interface device including a power interface and a data interface. The ground fault interface device is structured to output power via the power interface and to receive data via the data interface. The ground fault monitoring system also includes a plurality of ground fault devices structured to detect a ground fault on an associated circuit, to output data of the detected ground fault to the ground fault interface device, and to receive power to operate the ground fault devices via power lines. The plurality of ground fault devices are electrically connected in a series connection with the ground fault interface device by data lines and power lines. Each of the ground fault devices is configured to pass through received data and power.

BACKGROUND

1. Field

The disclosed concept pertains generally to ground fault monitoringsystems, and, more particularly, to ground fault monitoring systemsincluding multiple ground fault devices.

2. Background Information

Ground faults in circuits occur when electricity flowing through thecircuit travels to ground outside an intended grounding path. Groundfaults are typically detected by using a pair of current sensors (e.g.,without limitation, current transformers) to determine whether currentflowing through line and neutral conductors is equal. Unequal currentflowing through the line and neutral conductors can indicate that thereis a ground fault in the circuit.

Ground faults in the circuit can be hazardous, and thus it is importantthat they are detected. In applications where multiple circuits must bemonitored for ground fault such as, without limitation, marina powersystems, it is beneficial to ascertain the status of all of the circuitsfrom a central location.

One type of existing ground fault monitoring system includes a groundfault monitor and multiple associated ground fault relays, an example ofwhich is shown in FIG. 1.

As shown in FIG. 1, the system includes a ground fault monitor 2 andmultiple ground fault relays 12. The ground fault relays 12 are eachconfigured to electrically connect to associated current transformers14. The current transformers 14 are used to sense current flowingthrough the circuits. Based on the inputs of the current transformers14, the ground fault relays 12 can detect ground faults in the circuits.The ground fault relays 12 relay information about any ground faults inthe circuits back to the ground fault monitor 2 where a user of thesystem can access the information.

The ground fault monitor 2 includes multiple input connectors 4, 6, 8,10. Each input connector 4, 6, 8, 10 is configured to allow a connectionto one associated ground fault relay 12. As shown in FIG. 1, three ofthe input connectors 4, 6, 8 are used to electrically connect the groundfault monitor 2 to the three associated ground fault relays 12. One ofthe input connectors 10 is not electrically connected to an associatedground fault relay 12. The system of FIG. 1 is able to accommodate oneadditional ground fault relay 12 electrically connected to the groundfault monitor 2 for a maximum of four ground fault relays 12. Thus, thenumber of ground fault relays 12 that may be electrically connected tothe ground fault monitor 2 is limited by the number of input connectors4, 6, 8, 10 that are included in the ground fault monitor 2.

Using the ground fault monitor 2 with the fixed number of inputconnectors 4, 6, 8, 10 can be inefficient. For example, the number ofground fault relays 12 that are needed in an application may be knownwhen selecting the ground fault monitor 2 with four input connectors 4,6, 8, 10. However, over time, the number of ground fault relays 12 thatare needed in the application may grow. If the ground fault monitor 2does not include enough input connectors 4, 6, 8, 10 for the newlyneeded ground fault relays 12, a ground fault monitor with more inputconnectors or a second ground fault monitor would be needed.Additionally, initially selecting the ground fault monitor 2 withadditional unused input connectors 4, 6, 8, 10, which is likely morecomplex and expensive than a ground fault monitor with a smaller numberof input connectors, requires speculation into the potential expansionof the number of ground fault relays 12 that are needed. In the casethat the number of ground fault relays 12 that are needed does notexpand as much as expected, a ground fault monitor with a smaller numberof input connectors could have initially been selected to save cost.Moreover, in the case that the number of ground fault relays 12 that areneeded expands more than expected, a ground fault monitor with moreinput connectors or a second ground fault monitor would still need to beacquired despite planning for the anticipated expansion of theapplication, thus increasing the cost of the system.

There is therefore room for improvement in ground fault monitoringsystems.

SUMMARY

These needs and others are met by embodiments of the disclosed concept,which are directed to a ground fault monitoring system in which thenumber of ground fault devices associated with a ground fault interfacedevice may be expanded without the need for additional input interfacesin the ground fault interface device.

In accordance with one aspect of the disclosed concept a ground faultmonitoring system comprises: a plurality of data lines; a plurality ofpower lines; a ground fault interface device including a power interfacestructured to connect to one of the power lines and a data interfacestructured to connect to one of the data lines, wherein the ground faultinterface device is structured to output power via the power interfaceand to receive data via the data interface; a plurality of ground faultdevices structured to detect a ground fault on an associated circuit, tooutput data of the detected ground fault to the ground fault interfacedevice via the data lines, and to receive power to operate the groundfault devices via the power lines, wherein the plurality of ground faultdevices are electrically connected in a series connection with theground fault interface device by the plurality of data lines and theplurality of power lines, wherein each of the plurality of ground faultdevices is configured to pass through data received via the data linesto a previous one of the plurality of ground fault devices in the seriesconnection if the ground fault device is not first in the seriesconnection and to pass through data received via the data lines to theground fault interface device if the ground fault device is first in theseries connection, and wherein each of the plurality of ground faultdevices is configured to pass through power received via the power linesto a next one of the plurality of ground fault devices in the seriesconnection.

In accordance with another aspect of the disclosed concept a groundfault monitoring system comprises: a plurality of power lines; a groundfault interface device including a power interface structured to connectto one of the power lines and a wireless receiver structured to receivewirelessly transmitted data, wherein the ground fault interface deviceis structured to output power via the power interface; a plurality ofground fault devices structured to detect a ground fault on anassociated circuit and to receive power to operate the ground faultdevices via the power lines, wherein each of the plurality of groundfault devices includes a wireless transmitter structured to output thedata of the detected ground fault to the wireless transmitter includedin the ground fault interface device, wherein the plurality of groundfault devices are electrically connected in a series connection with theground fault interface device by the plurality of power lines, andwherein each of the plurality of ground fault devices is configured topass through power received via the power lines to a next one of theplurality of ground fault devices in the series connection.

In accordance with a further aspect of the disclosed concept a groundfault monitoring system comprises: a ground fault interface deviceincluding a wireless receiver structured to receive wirelesslytransmitted data; a plurality of ground fault devices structured todetect a ground fault on an associated circuit, wherein each of theplurality of ground fault devices includes a wireless transmitterstructured to output the data of the detected ground fault to thewireless transmitter included in the ground fault interface device,wherein each of the plurality of ground fault devices includes a powerinput interface structured to electrically connect to and receive powerfrom a corresponding power source, and wherein each of the plurality ofground fault devices is structured to use power received via the powerinterface to operate the ground fault device.

BRIEF DESCRIPTION OF THE DRAWINGS

A full understanding of the disclosed concept can be gained from thefollowing description of the preferred embodiments when read inconjunction with the accompanying drawings in which:

FIG. 1 is a block diagram of a prior ground fault monitoring system;

FIG. 2 is a block diagram of a ground fault monitoring system inaccordance with an example embodiment of the disclosed concept;

FIG. 3 is a block diagram of a ground fault monitoring system inaccordance with another example embodiment of the disclosed concept;

FIG. 4 is a block diagram of a ground fault monitoring system inaccordance with another example embodiment of the disclosed concept; and

FIG. 5 is a block diagram of a ground fault interface device inaccordance with an example embodiment of the disclosed concept.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Directional phrases used herein, such as, for example, left, right,front, back, top, bottom and derivatives thereof, relate to theorientation of the elements shown in the drawings and are not limitingupon the claims unless expressly recited therein.

As employed herein, the term “number” shall mean one or an integergreater than one (i.e., a plurality).

As employed herein, the statement that two or more parts are “coupled”together shall mean that the parts are joined together either directlyor joined through one or more intermediate parts.

As employed herein, the term “processor” shall mean a programmableanalog and/or digital device that can store, retrieve, and process data(e.g., without limitation, a computer; a workstation; a personalcomputer; a controller; a digital signal processor; a microprocessor; amicrocontroller; a microcomputer; a central processing unit; a mainframecomputer; a mini-computer; a server; a networked processor; aprogrammable logic controller; or any suitable processing device orapparatus).

FIG. 2 is a block diagram of a ground fault monitoring system 20 inaccordance with an example embodiment of the disclosed concept. Theground fault monitoring system 20 includes a ground fault interfacedevice 21 and three ground fault devices 26. While three ground faultdevices 26 are disclosed in the example embodiment of the disclosedconcept shown in FIG. 2, it will be appreciated by those having ordinaryskill in the art that any number of ground fault devices 26 may beemployed in the ground fault monitoring system 20 without departing fromthe scope of the disclosed concept.

The ground fault interface device 21 includes a data interface 22 and apower interface 24. The data interface 22 is structured to connect to adata line 23 (e.g., without limitation, a cable suitable to carry a datatransmission). The ground fault interface device 21 is configured toreceive data from the ground fault devices 26 via the data interface 22.The data interface 22 may be, without limitation, a connector, aterminal, a port, or any other suitable interface to electricallyconnect the data line 23 with the ground fault interface device 21.

The power interface 24 is structured to connect to a power line 25(e.g., without limitation, a cable suitable to carry a powertransmission). The ground fault interface device 24 is structured tooutput power to the ground fault devices 26 via the power interface 24.The power interface 24 may be, without limitation, a connector, aterminal, a port, or any other suitable interface to electricallyconnect the power line 25 with the ground fault interface device 21.

The ground fault devices 26 are structured to detect ground faults oncircuits (not shown) associated with the ground fault devices 26. Theground fault devices 26 are also structured to output data of detectedground faults to the ground fault interface device 21 via the data lines23. The ground fault devices 26 are also structured to receive power tooperate themselves via the power lines 25.

The ground fault devices 26 are electrically connected in a seriesconnection with the ground fault interface device 21 by the data lines23 and the power lines 25.

The ground fault devices 26 each include a data input interface 28 and adata output interface 30. The data input and output interfaces 28,30 arestructured to allow data lines 23 to be connected to the ground faultdevice 26. The ground fault devices 26 are configured to output data tothe ground fault interface device 21 or another ground fault device 26via the data output interface 30 and the data lines 23. The ground faultdevices 26 are also configured to receive data from another ground faultdevice 26 via the data input interface 28. The ground fault devices 26are further configured to pass through data received via the data lines23 at the data input interface 28, and to output the received data atthe data output interface 30. Thus, if the ground fault device 26 is notthe first in the series connection of ground fault devices 26, the datawill be passed through to the previous ground fault device 26 in theseries connection. Thus, the data output by one of the ground faultdevices 26 will continue to be passed through each ground fault device26 in the series connection unit it reaches the first ground faultdevice 26 in the series connection which will pass through the data tothe ground fault interface device 21.

The ground fault devices 26 may use any suitable communication protocolto communicate with the ground fault interface device 21. In someexample embodiments of the disclosed concept, the ground fault devices26 use, without limitation, an EtherNet Internet Protocol (IP) or ModbusTransmission Control Protocol (TCP) communication protocol tocommunicate with the ground fault interface device 21.

The ground fault devices 26 each also include a power input interface 32and a power output interface 34. The power input and output interfaces32,34 are structured to allow the ground fault devices 26 to beconnected to power lines 25. The ground fault devices 26 are structuredreceive power from the ground fault interface device 21 via the powerinput interface 32. The ground fault devices 26 are configured to usethe power received via the power input interface 32 to power their ownoperations. The ground fault devices 26 are also structured to passthrough power received at the power input interface 32 and output it tothe next ground fault device 26 in the series connection via the poweroutput interface 34. In this manner, power output via the powerinterface 24 of the ground fault interface device 21 will be passedalong through all of the ground fault devices 26 and thus can be used topower operation of all of the ground fault devices 26.

In the example embodiment of the disclosed concept shown in FIG. 2,three ground fault devices 26 are shown. However, additional groundfault devices 26 may be added to the ground fault monitoring system byconnecting the data output interface 30 and the power input interface 32of the additional ground fault device 26 to the data input interface 28and the power output interface 34 of the last ground fault device 26 inthe chain of ground fault devices 26. Expanding the number of groundfault devices 26 used in the ground fault monitoring system 20 does notnecessitate any additional data or power interfaces 22,24 in the groundfault interface device 21 since both power and data are passed throughthe ground fault devices 21. Thus, the number of ground fault devices 26that may be employed in the ground fault monitoring system 20 is notconstrained by the number of data and power interfaces 22,24 in theground fault interface device 21. As such, it will be appreciated bythose having ordinary skill in the art that any number of ground faultdevices 26 may be employed in the ground fault monitoring system 20without departing from the scope of the disclosed concept.

The ground fault devices 26 are each configured to electrically connectto pair of current transformers 36. The current transformers 36 are thenbe used to sense current flowing through the circuits (not shown)associated with the ground fault device 26. The ground fault devices 26are configured to detect ground faults in the circuits based on theinputs of the current transformers 36. The ground fault devices 26 arealso configured to transmit data of the ground faults to the groundfault interface device 21, either directly or through another groundfault device 26, via the data output interface 30. The data of theground faults may then be accessed by a user of the ground faultmonitoring system 20 at the ground fault interface device 21.

In some example embodiments of the disclosed concept, the ground faultdevices 26 are configured to output data on detected ground faultcurrents to the ground fault interface device 21 via the data lines 23.The ground fault interface devices 26 may be configured to output asignal to the ground fault interface device 21 that is proportional tothe amount of ground fault current sensed by the ground fault device 26.

The ground fault devices 26 include a trip output interface 37. In someexample embodiments of the disclosed concept, the trip output interface37 is configured to output a trip signal to an associated circuitbreaker (not shown) to cause the circuit breaker to trip. The groundfault devices 26 may be configured to automatically output the tripsignal when a ground fault current above a predetermined level isdetected. The ground fault interface device 21 may also control theground fault devices 26 to output the trip signal. In some other exampleembodiments of the disclosed concept, the trip output interface 37 isconfigured to output an alarm signal.

In some example embodiments of the disclosed concept, the ground faultdevices 26 are addressed so that the ground fault interface device 21can recognize which ground fault device 26 it is receiving a signalfrom. The ground fault devices 26 may use any suitable addressingscheme. In some example embodiments of the disclosed concept, the groundfault devices 26 are addressed through the use of static IP addresses.

In some example embodiments of the disclosed concept, the ground faultinterface device 21 is configured to receive data on detected groundfault currents from the ground fault interface devices 26. The groundfault interface device 21 is also configured to sum the ground faultcurrents detected by a group of the ground fault interface devices 26(e.g., without limitation, the ground fault interface devices 26corresponding to a defined zone) and to control the group of groundfault devices 26 to output trip signals when the sum of the ground faultcurrents exceeds a predetermined value.

It is contemplated that the ground fault devices 26 and/or the groundfault interface device 21 may include a processor (not shown). Theprocessor may be, for example and without limitation, a microprocessor,a microcontroller, or some other suitable processing device orcircuitry, that interfaces with the memory. It is also contemplated thatground fault devices 26 and/or the ground fault interface device 21 mayinclude a memory (not shown). The memory may be any of one or more of avariety of types of internal and/or external storage media such as,without limitation, RAM, ROM, EPROM(s), EEPROM(s), FLASH, and the likethat provide a storage register, i.e., a machine readable medium, fordata storage such as in the fashion of an internal storage area of acomputer, and can be volatile memory or nonvolatile memory. It iscontemplated that the processor and/or memory may be employed toimplement one or more operations of the ground fault devices 26 and/orthe ground fault interface device 21 such as, without limitation,gathering data, transmitting data, analyzing data, and displaying data.

In some example embodiments of the disclosed concept, the ground faultinterface device 21 is configured to output signals such as, withoutlimitation, data of ground faults on the circuits, to other devices suchas, without limitation, shunt trip units or alarms.

FIG. 3 is a block diagram of a ground fault monitoring system 20′ inaccordance with another example embodiment of the disclosed concept. Theground fault monitoring system 20′ of FIG. 3 is similar to the groundfault monitoring system 20 of FIG. 2. However, the ground faultmonitoring system 20′ of FIG. 3 includes a ground fault interface device21 including a wireless receiver 38 and ground fault devices 26′ eachincluding a wireless transmitter 40.

The wireless transmitters 40 are configured to transmit data of groundfaults to the wireless receiver 38. The wireless receiver 38 andwireless transmitters 40 may communicate using any suitable wirelesscommunication protocol. Furthermore, it is contemplated that thewireless receiver 38 and wireless transmitters 40 may use any type ofwireless communication (e.g., without limitation, radio, optical, sonic,etc.) without departing from the scope of the disclosed concept.

The wireless transmission of data between the ground fault devices 26′and the ground fault interface device 21′, the data interface 24, datalines 25, data input interface 28, and data output interface 30 (seeFIG. 2) may be omitted from the ground fault monitoring system 20′ ofFIG. 3 while still allowing any number of ground fault devices 26′ to beadded to the ground fault monitoring system 20′.

FIG. 4 is a block diagram of a ground fault monitoring system 20″ inaccordance with another example embodiment of the disclosed concept. Theground fault monitoring system 20″ of FIG. 4 is similar to the groundfault monitoring system 20′ of FIG. 3. However, in the ground faultmonitoring system 20″ of FIG. 4, the power input interfaces 32 of theground fault monitoring devices 26″ are electrically connected to powersources 42.

The power sources 42 may be utility power or any other power sourcesuitable to provide power to operate the ground fault devices 26″. Thus,the ground fault devices 26″ may be electrically connected to powersources 42 in their vicinity, rather than to each other.

In this example embodiment of the disclosed concept, the wirelesstransmitters 40 in the ground fault devices 26″ and the wirelessreceiver 38 in the ground fault interface device 21″ allow the groundfault devices 26″ to wirelessly communicated data to the ground faultinterface device 21″. Furthermore, the ground fault devices 26″ mayreceive power from the power sources 42 directly, rather than via theground fault interface device 21″ or other ground fault devices 26″. Assuch, in this example embodiment of the disclosed concept, wiringbetween the ground fault interface device 21″ and the ground faultdevices 26″ or between one of the ground fault devices 26″ and anotherof the ground fault devices 26″ is not needed.

FIG. 5 is a block diagram of the ground fault interface device 21 ofFIG. 2. As shown in FIG. 5, the ground fault interface device 21 mayinclude a display 44. The display 44 may be any suitable type of displaysuch as, without limitation, a liquid crystal display (LCD) or a lightemitting diode (LED) display. The display 44 is configured to displaythe data received from the ground fault devices 26 (see FIG. 2) so thatthe user of the ground fault monitoring system 20 can determine whetherthere are any ground faults on the monitored circuits. The display 44may also be a touch screen type display that is able to receive inputsfrom the user of the ground fault monitoring system 20.

While specific embodiments of the disclosed concept have been describedin detail, it will be appreciated by those skilled in the art thatvarious modifications and alternatives to those details could bedeveloped in light of the overall teachings of the disclosure.Accordingly, the particular arrangements disclosed are meant to beillustrative only and not limiting as to the scope of the disclosedconcept which is to be given the full breadth of the claims appended andany and all equivalents thereof.

What is claimed is:
 1. A ground fault monitoring system comprising: aplurality of data lines; a plurality of power lines; a ground faultinterface device including a power interface structured to connect toone of the power lines and a data interface structured to connect to oneof the data lines, wherein the ground fault interface device isstructured to output power via the power interface and to receive datavia the data interface; and a plurality of ground fault devices eachstructured to detect a ground fault on an associated circuit, to outputdata of the detected ground fault to the ground fault interface devicevia the data lines, and to receive power to operate the ground faultdevices via the power lines, wherein the plurality of ground faultdevices are electrically connected in a series connection with theground fault interface device by the plurality of data lines and theplurality of power lines, wherein each of the plurality of ground faultdevices is configured to pass through data received via the data linesto a previous one of the plurality of ground fault devices in the seriesconnection if the ground fault device is not first in the seriesconnection and to pass through data received via the data lines to theground fault interface device if the ground fault device is first in theseries connection, and wherein each of the plurality of ground faultdevices is configured to pass through power received via the power linesto a next one of the plurality of ground fault devices in the seriesconnection.
 2. The ground fault monitoring system of claim 1, whereineach of the ground fault devices includes: a data input interfacestructured to connect to one of the data lines and to receive data; adata output interface structured to connect to one of the data lines andto output data; a power input interface structured to connect to one ofthe power lines and to receive power; and a power output interfacestructured to connect to one of the power lines and to output power,wherein the ground fault device is configured to pass through datareceived at the data input interface and to output said data at the dataoutput interface, and wherein the ground fault device is configured topass through power received at the power input interface and to outputsaid power at the power output interface.
 3. The ground fault monitoringsystem of claim 1, further comprising: a plurality of current sensors,wherein each of the ground fault devices is electrically connected to acorresponding two of the current sensors, and wherein the ground faultdevices are structured to detect ground faults on the associatedcircuits based on outputs of the current sensors.
 4. The ground faultmonitoring system of claim 1, wherein the data of the detected groundfault includes a ground fault current level on the associated circuit.5. The ground fault monitoring system of claim 1, wherein each of theground fault devices includes a trip output interface; and wherein eachof the ground fault devices is configured to output a trip signal to anassociated circuit breaker via the trip output interface.
 6. The groundfault monitoring system of claim 5, wherein the ground fault interfacedevice is structured to control the ground fault devices to output thetrip signal.
 7. The ground fault monitoring system of claim 5, whereinthe ground fault devices are each configured to output the trip signalwhen a detected ground fault current on the associated circuit exceeds apredetermined value.
 8. The ground fault monitoring system of claim 1,wherein the ground fault interface device includes a display structuredto display data received from the ground fault devices.
 9. The groundfault monitoring system of claim 1, wherein the plurality of groundfault devices includes at least three ground fault devices.
 10. A groundfault monitoring system comprising: a plurality of power lines; a groundfault interface device including a power interface structured to connectto one of the power lines and a wireless receiver structured to receivewirelessly transmitted data, wherein the ground fault interface deviceis structured to output power via the power interface; and a pluralityof ground fault devices structured to detect a ground fault on anassociated circuit and to receive power to operate the ground faultdevices via the power lines, wherein each of the plurality of groundfault devices includes a wireless transmitter structured to output thedata of the detected ground fault to the wireless transmitter includedin the ground fault interface device, wherein the plurality of groundfault devices are electrically connected in a series connection with theground fault interface device by the plurality of power lines, andwherein each of the plurality of ground fault devices is configured topass through power received via the power lines to a next one of theplurality of ground fault devices in the series connection.
 11. Theground fault monitoring system of claim 10, wherein each of the groundfault devices includes: a power input interface structured to connect toone of the power lines and to receive power; and a power outputinterface structured to connect to one of the power lines and to outputpower, wherein the ground fault device is configured to pass throughpower received at the power input interface and to output said power atthe power output interface.
 12. The ground fault monitoring system ofclaim 10, further comprising: a plurality of current sensors, whereineach of the ground fault devices is electrically connected to acorresponding two of the current sensors, and wherein the ground faultdevices are structured to detect ground faults on the associatedcircuits based on outputs of the current sensors.
 13. The ground faultmonitoring system of claim 10, wherein the data of the detected groundfault includes a ground fault current level on the associated circuit.14. The ground fault monitoring system of claim 10, wherein the groundfault interface device includes a display structured to display datareceived from the ground fault devices.
 15. The ground fault monitoringsystem of claim 10, wherein each of the ground fault devices includes atrip output interface; and wherein each of the ground fault devices isconfigured to output a trip signal to an associated circuit breaker viathe trip output interface.
 16. The ground fault monitoring system ofclaim 10, wherein the plurality of ground fault devices includes atleast three ground fault devices.
 17. A ground fault monitoring systemcomprising: a ground fault interface device including a wirelessreceiver structured to receive wirelessly transmitted data; and aplurality of ground fault devices structured to detect a ground fault onan associated circuit, wherein each of the plurality of ground faultdevices includes a wireless transmitter structured to output the data ofthe detected ground fault to the wireless transmitter included in theground fault interface device, wherein each of the plurality of groundfault devices includes a power input interface structured toelectrically connect to and receive power from a corresponding powersource, and wherein each of the plurality of ground fault devices isstructured to use power received via the power interface to operate theground fault device.
 18. The ground fault monitoring system of claim 17,further comprising: a plurality of current sensors, wherein each of theground fault devices is electrically connected to a corresponding two ofthe current sensors, and wherein the ground fault devices are structuredto detect ground faults on the associated circuits based on outputs ofthe current sensors.
 19. The ground fault monitoring system of claim 17,wherein the data of the detected ground fault includes a ground faultcurrent level on the associated circuit.
 20. The ground fault monitoringsystem of claim 17, wherein the ground fault interface device includes adisplay structured to display data received from the ground faultdevices.
 21. The ground fault monitoring system of claim 17, whereineach of the ground fault devices includes a trip output interface; andwherein each of the ground fault devices is configured to output a tripsignal to an associated circuit breaker via the trip output interface.22. The ground fault monitoring system of claim 17, wherein theplurality of ground fault devices includes at least three ground faultdevices.